Brain tumors in children--current therapies and newer directions

Genetically modified ZIKA virus as a microRNA-sensitive oncolytic virus against central nervous system tumors

Here we introduce a first-in-class microRNA-sensitive oncolytic Zika virus (ZIKV) for virotherapy application against central nervous system (CNS) tumors. The described methodology produced two synthetic modified ZIKV strains that are safe in normal cells, including neural stem cells, while preserving brain tropism and oncolytic effects in tumor cells. The microRNA-sensitive ZIKV introduces genetic modifications in two different virus sites: first, in the established 3'UTR region, and secondly, in the ZIKV protein coding sequence, demonstrating for the first time that the miRNA inhibition systems can be functional outside the UTR RNA sites. The total tumor remission in mice bearing human CNS tumors, including metastatic tumor growth, after intraventricular and systemic modified ZIKV administration, confirms the promise of this virotherapy as a novel agent against brain tumors-highly deadly diseases in urgent need of effective advanced therapies.

Cerebellar irradiation does not cause hyperactivity, fear, and anxiety-related disorders in the juvenile rat brain

Background

The cerebellum is involved in hyperactivity, fear, and anxiety disorders that could be induced by whole-brain irradiation (WBI). However, whether cerebellar irradiation alone (CIA) could induce these disorders is unknown. We investigated the effect of CIA in an animal model.

Methods

Eleven-day-old rat pups underwent a single 3-Gy dose of either WBI (n = 28) or CIA (n = 20), while 34 rat pups were sham-irradiated (controls). Cell death was evaluated in the subgranular zone of the hippocampus by counting pyknotic cells after haematoxylin/eosin staining at 6 h after irradiation for 10, 8, and 9 pups, respectively. Behavioural changes were evaluated via open-field test at 6 weeks for 18, 12, and 25 pups, respectively. Unpaired two-tailed t-test and one-way and two-way repeated ANOVA were used.

Results

Massive cell death in cerebellar external granular layer was detected at 6 h after CIA (1,419 ± 211 mm, mean ± S.E.M. versus controls (68 ± 12 mm) (p < 0.001)), while no significant difference between CIA (1,419 ± 211 mm) versus WBI (1,433 ± 107 mm) (p = 0.955) was found. At open-field behavioural test, running distance, activity, wall distance, middle zone visit times, and duration were higher for WBI versus controls (p < 0.010), but no difference between CIA and controls was found (p > 0.05).

Conclusions

Although the cerebellum is involved in hyperactivity, fear, and anxiety disorders, CIA did not induce these disorders, indicating that WBI-induced cerebellar injury does not directly cause these behavioural abnormalities after WBI. Thus, targeting the cerebellum alone may not be enough to rescue or reduce these behavioural abnormalities after WBI.

Nimotuzumab therapy in the treatment of pediatric central nervous system tumors: single-center experience

Relapsed or refractory central nervous system (CNS) tumors still have poor prognosis, and, therefore, new treatment options are required. We retrospectively researched treatment results of patients with CNS tumors treated with nimotuzumab from 2010 to 2015. The study included nine patients with the diffuse intrinsic pontine glioma; eight with medulloblastoma; three each with anaplastic ependymoma, glioblastoma multiforme, and central nervous system primitive neuroectodermal tumor (CNS PNET); two patients with gliomatosis cerebri; and one patient each with other tumor types, including atypical teratoid rhabdoid tumor, thalamic astrocytoma, low-grade glial tumor, high-grade glial tumor, and cribriform neuroepithelial tumor. An objective response was observed in 10 of 33 patients with four patients showing a complete response, three a partial response, and three patients had stable disease. The 2-year overall survival (OS) and progression-free survival (PFS) rates were 35 ±9% and 19 ±8%, respectively. Due to the objective response in medulloblastoma, CNS PNET, and anaplastic ependymoma (MED group), survival rates of this group were analyzed. The 2-year OS and PFS for the MED group were 71 ±12% and 30 ±13%, respectively. The treatment was well tolerated. The treatment responses for medulloblastoma, CNS PNET, and anaplastic ependymoma have been promising. Likewise, some patients with relapsed or progressive CNS tumors may benefit through nimotuzumab-containing regimen.

Radiation Triggers a Dynamic Sequence of Transient Microglial Alterations in Juvenile Brain

Cranial irradiation (IR), an effective tool to treat malignant brain tumors, triggers a chronic pro-inflammatory microglial response, at least in the adult brain. Using single-cell and bulk RNA sequencing, combined with histology, we show that the microglial response in the juvenile mouse hippocampus is rapid but returns toward normal within 1 week. The response is characterized by a series of temporally distinct homeostasis-, sensome-, and inflammation-related molecular signatures. We find that a single microglial cell simultaneously upregulates transcripts associated with pro- and anti-inflammatory microglial phenotypes. Finally, we show that juvenile and adult irradiated microglia are already transcriptionally distinct in the early phase after IR. Our results indicate that microglia are involved in the initial stages but may not be responsible for driving long-term inflammation in the juvenile brain.

STAT3 is a key molecule in the oncogenic behavior of diffuse intrinsic pontine glioma

Diffuse intrinsic pontine glioma (DIPG) is one of the most lethal childhood brain tumors. This tumor is unique because it is detected exclusively in the ventral pons of patients aged between 6 and 7 years, which suggests a developmental nature of its formation. Signal transducer and activator of transcription 3 (STAT3) is a critical molecule for the differentiation of neural stem cells into astrocytes during neurodevelopment. Additionally, STAT3 is associated with oncogenesis and the epithelial-mesenchymal transition (EMT) in various types of tumor. In recent years, several studies have demonstrated the oncogenic role of STAT3 in high-grade gliomas. However, the role of STAT3 in DIPG at the cellular level remains unknown. To assess the possible association between gliogenesis and DIPG, the expression levels of various molecules participating in the differentiation of neural stem cells were compared between normal brain control tissues and DIPG tissues using open public data. All of the screened genes exhibited significantly increased expression in DIPG tissues compared with normal tissues. As STAT3 expression was the most increased, the effect of STAT3 inhibition in a DIPG cell line was assessed via STAT3 short hairpin (sh)RNA transfection and treatment with AG490, a STAT3 inhibitor. Changes in viability, apoptosis, EMT and radiation therapy efficiency were also evaluated. Downregulation of STAT3 resulted in decreased cyclin D1 expression and cell viability, migration and invasion. Additionally, treatment with STAT3 shRNA or AG490 suppressed the EMT phenotype. Finally, when radiation was administered in combination with STAT3 inhibition, the therapeutic efficiency, assessed by cell viability and DNA damage repair, was increased. The present results suggest that STAT3 is a potential therapeutic target in DIPG, especially when combined with radiation therapy.

Dendritic Cell-Based and Other Vaccination Strategies for Pediatric Cancer

Dendritic cell-based and other vaccination strategies that use the patient’s own immune system for the treatment of cancer are gaining momentum. Most studies of therapeutic cancer vaccination have been performed in adults. However, since cancer is one of the leading causes of death among children past infancy in the Western world, the hope is that this form of active specific immunotherapy can play an important role in the pediatric population as well. Since children have more vigorous and adaptable immune systems than adults, therapeutic cancer vaccines are expected to have a better chance of creating protective immunity and preventing cancer recurrence in pediatric patients. Moreover, in contrast to conventional cancer treatments such as chemotherapy, therapeutic cancer vaccines are designed to specifically target tumor cells and not healthy cells or tissues. This reduces the likelihood of side effects, which is an important asset in this vulnerable patient population. In this review, we present an overview of the different therapeutic cancer vaccines that have been studied in the pediatric population, with a main focus on dendritic cell-based strategies. In addition, new approaches that are currently being investigated in clinical trials are discussed to provide guidance for further improvement and optimization of pediatric cancer vaccines.

Chemical modulation of autophagy as an adjunct to chemotherapy in childhood and adolescent brain tumors

Brain tumors are the leading cause of cancer-related death in children and are the most challenging childhood cancer in relation to diagnosis, treatment, and outcome. One potential novel strategy to improve outcomes in cancer involves the manipulation of autophagy, a fundamental process in all cells. In cancer, autophagy can be thought of as having a "Janus"-like duality. On one face, especially in the early phases of cancer formation, autophagy can act as a cellular housekeeper to eliminate damaged organelles and recycle macromolecules, thus acting as tumor suppressor. On the other face, at later stages of tumor progression, autophagy can function as a pro-survival pathway in response to metabolic stresses such as nutrient depravation, hypoxia and indeed to chemotherapy itself, and can support cell growth by supplying much needed energy. In the context of chemotherapy, autophagy may, in some cases, mediate resistance to treatment. We present an overview of the relevance of autophagy in central nervous system tumors including how its chemical modulation can serve as a useful adjunct to chemotherapy, and use this knowledge to consider how targeting of autophagy may be relevant in pediatric brain tumors.

Outcome of young children with high-grade glioma treated with irradiation-avoiding intensive chemotherapy regimens: Final report of the Head Start II and III trials

PURPOSE

To report the final analysis of survival outcomes for children with newly diagnosed high-grade glioma (HGG) treated on the "Head Start" (HS) II and III protocols with chemotherapy and intent to avoid irradiation in children <6 years old.

PATIENTS AND METHODS

Between 1997 and 2009, 32 eligible children were enrolled in HS II and III with anaplastic astrocytoma (AA, n = 19), glioblastoma multiforme (GBM, n = 11), or other HGG (n = 2). Central pathology review was completed on 78% of patients. Patients with predominantly brainstem tumors were excluded. Patients were to be treated with single induction chemotherapy regimen C, comprising four cycles of vincristine, carboplatin, and temozolomide. Following induction, patients underwent marrow-ablative chemotherapy and autologous hematopoietic cell rescue. Irradiation was used for patients with residual tumor after consolidation or >6 years old or at the time of tumor progression.

RESULTS

The 5-year event-free survival (EFS) and overall survival (OS) for all HGG patients were 25 ± 8% and 36 ± 9%, respectively. The EFS at 5 years for patients with AA and GBM were 24 ± 11% and 30 ± 16%, respectively (P = 0.65). The OS at 5 years for patients with AA and GBM was 34 ± 12% and 35 ± 16%, respectively (P = 0.83). Children <36 months old experienced improved 5-year EFS and OS of 44 ± 17% and 63 ± 17%, compared with children 36-71 months old (31 ± 13% and 38 ± 14%) and children >72 months old (0% and 13 ± 12%).

CONCLUSIONS

Irradiation-avoiding treatment strategies should be evaluated further in young children with HGG given similar survival rates to older children receiving standard irradiation-containing therapies.

Improving Care in Pediatric Neuro-oncology Patients: An Overview of the Unique Needs of Children With Brain Tumors

Brain tumors represent the most common solid tumors in childhood, accounting for almost 25% of all childhood cancer, second only to leukemia. Pediatric central nervous system tumors encompass a wide variety of diagnoses, from benign to malignant. Any brain tumor can be associated with significant morbidity, even when low grade, and mortality from pediatric central nervous system tumors is disproportionately high compared to other childhood malignancies. Management of children with central nervous system tumors requires knowledge of the unique aspects of care associated with this particular patient population, beyond general oncology care. Pediatric brain tumor patients have unique needs during treatment, as cancer survivors, and at end of life. A multidisciplinary team approach, including advanced practice nurses with a specialty in neuro-oncology, allows for better supportive care. Knowledge of the unique aspects of care for children with brain tumors, and the appropriate interventions required, allows for improved quality of life.

The impact of surgical resection of giant supratentorial brain tumor in pediatric patients: safety and neurological outcome evaluated in 23 consecutive cases

OBJECTIVE

This study aims to evaluate the impact of gross total resection of giant supratentorial brain tumors (GSBT) on survival and neurological outcome in a consecutive single-center pediatric series.

METHODS

Clinical data of 23 patients under 18 years of age operated with GSBT (≥5 cm in diameter) were reviewed to determine epidemiological aspects, clinical presentation, associated factors, histopathological features, and outcome. Volumetric measurements were performed on magnetic resonance imaging or computed tomography scans obtained at the time of the initial surgical procedure.

RESULTS

The group included 23 patients (mean age 4.5 years). Signs and symptoms of raised intracranial pressure were present in 19 patients (82.6%). The most frequent tumor location was the parietal lobe in 19 patients (82.6%), and the mean tumor volume was 208 cm(3). Gross total or radical resection was achieved in all patients. Histopathological analysis revealed malignant brain tumors in 18 cases (78.2%). The most common neoplasm was choroid plexus carcinoma in seven (30.4 %). Mean intraoperative blood transfusion volume was 51.2 ml/kg. Chemotherapy and/or radiotherapy were performed as adjuvant treatment in 16 patients (69.5%). Mean length of follow-up was 36.7 months. Tumor malignancy grade significantly correlated with recurrence of the disease (P = 0.03) and death (P = 0.01), as opposed to tumor location, size, and extension to the ventricles.

CONCLUSIONS

Our clinical experience suggests that tumor mass reduction by en bloc surgery seems to be an effective approach in pediatric patients with GSBT, relieving symptoms related to raised intracranial pressure and providing a better response to adjuvant treatment.

Spectrum of pediatric brain tumors: a report of 341 cases from a tertiary cancer center in India

Brain tumors are the second most common cancers after hematological malignancies accounting for approximate 21% of all childhood malignancies in children between ages of 0 and 14 y. The present study was undertaken to determine the spectrum of the brain tumors diagnosed in a tertiary cancer center in South India. A retrospective analysis of the data of pediatric brain tumors diagnosed between 2003 and 2009 was done and data was classified according to the age, gender and histology types. Out of 2,844 pediatric patients, 341 (11.99%) were diagnosed as having brain tumors. Most of the patients were in the age group of >5-14 y. Male to female ratio was 1.58:1. The most common pediatric brain tumor was medulloblastoma followed by astrocytoma and ependymoma. Glioblastoma multiforme was the most common subtype of astrocytoma. Other common tumors were glioma, oligodendroglioma, periphereral neuroectodermal tumor and germ cell tumor. As compared to western data, incidence of brain tumors in children was found to be less in the present study.

Prolonged use of nimotuzumab in children with central nervous system tumors: safety and feasibility

Primary brain tumors constitute the most frequent solid tumor of childhood. High expression of the epidermal growth factor receptor (EGFR) protein has been associated with tumor progression and enhanced tumorigenicity in adult and children gliomas. Nimotuzumab is a humanized antibody that targets the EGFR and has proven efficacy in adult and children gliomas. To provide a new therapeutic option for patients with active, poor prognosis central nervous system (CNS) tumors and to evaluate the feasibility and safety of long-term nimotuzumab therapy in children with diverse CNS tumors, an expanded access program was launched at the Juan Manuel Marquez hospital. Patients were required to be 18 or younger and have one CNS tumor: low-grade glioma (LGG) or high-grade glioma (HGG), brainstem glioma (BSG), ependymoma or primitive neuroectodermal tumor (PNET), and a Lansky or Karnofsky performance status ≥40. Treatment consisted of weekly nimotuzumab administered at 150 mg/m(2) for 12 weeks, continuing every 14 days in the absence of severe condition worsening or unacceptable toxicity. Nimotuzumab was administered alone or in combination with radiotherapy, chemotherapy, or both, depending on the tumor type, stage, and previous treatment. Eighty-eight patients, 39 with BSG, 25 with HGG, 9 with progressive LGG, 9 with anaplastic ependymomas, and 6 with other tumor types, including PNET, neuroblastoma, meduloblastoma, and thalamic tumors, were treated with the antibody. The mean number of nimotuzumab doses was 36, from 1 to 108. The most frequent adverse events were mild to moderate skin rash, mucositis, vomiting, seizures, hypothermia, hyperthermia, and paleness. One patient had a grade 3 mucositis, while the other had a grade 3 bleeding on surgery. Sixteen children stopped treatment after at least 2 years with stable disease, partial or complete response. All children were able to maintain the best response achieved on treatment after a 3-year interruption. In summary, this study shows the feasibility of very prolonged administration of nimotuzumab together with the lack of rebound effect after treatment cessation.

Childhood cancers: what is a possible role of infectious agents?

The etiology of childhood cancers has been studied for more than 40 years. However, most if not all cancers occurring in children are attributed to unknown causes. This review is focused on the role of infections in cancer development and progression in children. The main infectious agents include human herpesviruses, polyoma viruses, and human papilloma viruses. It is known that infections can lead to carcinogenesis through various mechanisms, and most likely act in addition to genetic and environmental factors. Given the importance of the infectious etiology of childhood cancers, clinical implications and possible prevention strategies are discussed.

Treatment of children with high grade glioma with nimotuzumab: a 5-year institutional experience

Brain tumors are a major cause of cancer-related mortality in children. Overexpression of epidermal growth factor receptor (EGFR) is detected in pediatric brain tumors and receptor density appears to increase with tumor grading. Nimotuzumab is an IgG1 antibody that targets EGFR. Twenty-three children with high-grade glioma (HGG) were enrolled in an expanded access program in which nimotuzumab was administered alone or with radio-chemotherapy. The mean number of doses was 39. Nimotuzumab was well-tolerated and treatment with the antibody yielded a survival benefit: median survival time was 32.66 mo and the 2-y survival rate was 54.2%. This study demonstrated the feasibility of prolonged administration of nimotuzumab and showed preliminary evidence of clinical benefit in HGG patients with poor prognosis.

Overcoming the blood-brain barrier in chemotherapy treatment of pediatric brain tumors

Pediatric brain tumors are most common cancers in childhood and among the leading causes of death in children. Chemotherapy has been used as adjuvant (i.e. after) or neoadjuvant (i.e. before) therapy to surgery and radiotherapy for the management of pediatric brain tumors for more than four decades and gained more attention in the recent two decades. Although chemotherapy has demonstrated its effectiveness in the management of some pediatric brain tumors, failure or inactiveness of chemotherapy is commonly met in the clinics and clinical trials. Some of these failures might be attributed to the blood-brain barrier (BBB), limiting the penetration of systemically administered chemotherapeutics into pediatric brain tumors. Therefore, various strategies have been developed and used to address this issue. Herein, we review different methods reported in the literature to circumvent the BBB for enhancing the present of chemotherapeutics in the brain to treat pediatric brain tumors.

Detection of irreversible changes in susceptibility-weighted images after whole-brain irradiation of children

INTRODUCTION

Whole-brain irradiation is part of the therapy protocol for patients with medulloblastomas. Side effects and complications of radiation can be detected by follow-up magnetic resonance imaging (MRI). Susceptibility-weighted images (SWI) can detect even very small amounts of residual blood that cannot be shown with conventional MRI. The purpose of this study was to determine when and where SWI lesions appear after whole-brain irradiation.

METHODS

MRI follow-up of seven patients with medulloblastoma who were treated with whole-brain irradiation were analyzed retrospectively. SWI were part of the initial and follow-up MRI protocol. De novo SWI lesions, localization, and development over time were documented.

RESULTS

At time of irradiation, mean age of the patients was 13 years (±4 years). Earliest SWI lesions were detected 4 months after radiation treatment. In all patients, SWI lesions accumulated over time, although the individual number of SWI lesions varied. No specific dissemination of SWI lesions was observed.

CONCLUSION

Whole-brain irradiation can cause relatively early dot-like SWI lesions. The lesions are irreversible and accumulate over time. Histopathological correlation and clinical impact of these SWI lesions should be investigated.